Health spending by privately insured patients increased 4% last year, with households picking up more of the cost, new data show.

Spending per person among the privately insured increased $181 to $4,701 last year from the prior year, an analysis by the not-for-profit Health Care Cost Institute found. Institute researchers analyzed medical bills submitted to insurance giants Aetna, Humana and UnitedHealthcare for 2012 and three previous years in the report, which found slow growth continued last year among the commercially insured across all payers.

Last week, new federal data said overall health spending last year grew at a projected 3.9% for the fourth straight year.

Privately insured patients shouldered 16.3% of their healthcare costs out of their own pockets last year, compared with 16.1% in 2010, according to the Health Care Cost Institute.

The uptick underscores the increasing financial burden that households face as more employers adopt health plans that include high deductibles, coinsurance and other fees that leave patients to pay more of the medical bill. Out-of-pocket costs totaled $320.2 billion last year, an increase of 4.1% from the prior year, according to the federal estimates released last week. That figure includes spending by the uninsured and those with private or public insurance.

The Health Care Cost Institute said higher prices drove the increase in health spending last year by households with private insurance, though greater demand was behind increased spending for prescription drugs and procedures by medical professionals.

Hospital use continued to drop for those patients, while spending for outpatient services accelerated, said Carolina Herrera, the institute's director of research.

The number of patients admitted to the hospital fell 2.9% last year among privately insured patients, countering a 5.4% increase in inpatient prices, according to the Health Care Cost Institute. Herrera said hospitals' “bread and butter,” admissions for medical or surgical services, once again declined last year. Admissions in 2012 for mental health and substance abuse grew.

Among outpatient services, emergency room spending grew the fastest, increasing 10.8% last year, according to the cost institute's analysis.